The present invention relates to a device for controlling the operations of a medical fluidized bed for floating and supporting a human body, for purposes of medical treatment, on a bed of fine particles subjected to a flowing movement induced by a stream of compressed air diffused upwardly through a diffuser board.
Fluidized beds of the type described have principally been used in the medical field. The construction and operation of a fluidized bed will be described with reference to FIG. 1A. Ambient air AO is compressed and fed by a ring compressor 1 driven by a motor 1a, which has an increased temperature, is cooled to a prescribed temperature by a heat exchanger HC supplied with air from a fan F. Compressed air A1 directed via an air duct D is spread below a diffuser board 3 in a closed chamber 2.
The diffuser board 3, which is formed of a porous plate-like material, is provided for diffusing and spreading the compressed air A1 in the closed chamber 2 as diffused air moving upwardly through a multiplicity of gaps or interstices in the diffuser board 2 which are present throughout the entire area thereof. A bed 5 of fine particles or beads is subjected to a flowing movement by the diffused air 5. A tank 4 integral with the closed chamber 2 contains the bead bed 5 and the diffuser board 3. The upper surface of the bed 5 is covered with a sheet of cloth S having interstices smaller than the beads for allowing the diffused air A2 to pass therethrough while preventing the beads 5 from being dispersed. The sheet S also serves as a sheet of gauze or a bandage in contact with the patient resting thereon.
The fluidized bed is capable of preventing the interruption of blood circulation due to localized pressure exerted on the patient's body. Therefore, the bed has heretofore been used mainly for promoting the regrowth of skin of a badly burned patient or preventing bedsores in a patient bedridden for a long time. When the patient lies on the bed of flowing beads 5 with the sheet S interposed, the patient is supported evenly by the beads which undergo flowing movement below a wide area of the patient body. As a result, the surface pressure on the body is minimized, reducing pressure on the skin. Since the surface pressure is uniformly distributed, interruption of blood circulation due to localized pressure on peripheral blood vessels is avoided.
FIG. 1B illustrates the manner in which a human body is floatingly supported on the fluidized bed.
The conventional fluidized bed has a fixed height. However, there has been a demand for a fluidized bed having an adjustable height, specifically, one in which the height of the bed above the floor can be made as small as possible for ease in transferring a patient onto the bed or when a patient gets onto or off the bed, and placed at a suitable height when the patient is lying on the bed for administering treatment to the patient.
To meet this demand, it has been proposed to combine a lifter with the bed for adjusting the height of the bed. FIG. 2 illustrates the arrangement of such a mechanism for producing vertical movement.
The height of the fluidized bed, and hence the height of the tank 4, are freely adjustable by a lifter LF between a maximum height H1 and a minimum height H2. The lifter LF includes a link mechanism LK having bearings P1 and P2 fixed to ends thereof and rollers R1 and R2 on opposite ends thereof which are movable along a guide rail. A hydraulic cylinder OS serves as a vertical drive unit for extending and retracting the link mechanism LK. Vertical movement of such a vertically movable fluidized bed with a patient thereon while the beads 5 are in a flowing condition, however, results in the danger of causing the patient to move unnecessarily on the bed.